Field of the Disclosure
The present disclosure relates to photographic image acquisition devices and methods thereof, and in particular to still and video cameras having at least one imaging lens optically coupled to at least one image sensor that includes a focal plane array of photosensitive elements.
Description of the Related Art
Spatial resolution of photographic image acquisition devices is limited by the spatial resolution of the image sensor that includes a focal plane array of photosensitive elements, and the point spread function (optical blur) of the imaging lens optically coupled to the sensor.
There are two basic approaches to increasing the spatial resolution of the image sensor. The first is by raising the spatial density of the focal plane array, and the second is by increasing the optical format of the image sensor and the lens to accommodate a larger number of photosensitive elements.
The first approach requires size reduction of the photosensitive elements that causes a reduction in the number of photons collected by each photosensitive element per unit of time, and thus worsens the signal-to-noise ratio and the dynamic range of the image. Under the low light, the effective image resolution may drop due to the elevated image noise that drowns small image details, and due to an increased motion blur caused by a longer exposure time required to compensate for the elevated image noise. There is a hard physical limit on size reduction of the photosensitive elements imposed by light diffraction that has been already reached by the current sensor technology.
The second approach leads to an exponential cost increase of the image sensor due to an exponential dependency between the physical dimensions of the focal plane array and the fabrication cost. The same exponential cost increase applies to the corresponding large-format lenses.